This invention relates to surgical instruments, and to lasers used in such instruments.
During a surgical procedure, it is usually desirable to reduce the amount of blood discharged from an incised region of tissue. Application of radiation to the tissue following the incision results in coagulation, thereby reducing the amount of bleeding once the incision has been made.
Light sources, such as lasers, can be coupled to optical fibers and used to irradiate and heat the incised region in a controllable manner. Using this procedure, light of the appropriate wavelength is absorbed by the various components of the tissue, and optical energy is converted into thermal energy to heat and coagulate the incised region.
In principle, light sources can be combined with surgical instruments in two ways: in one method, the light source can be used in combination with a mechanical cutting device, such as a scalpel, and used to illuminate recently incised tissue. Such "laser scalpels" allow heating of tissue regions following, or in some cases during, the surgical procedure. Devices of this kind are described in U.S. Pat. Nos. 4,249,533; 4,266,577; and 4,195,633, among others. Alternatively, the light source can be used as a source for both ablation and coagulation. In this technique, ablation of tissue using high levels of radiation often results in undesirable tissue-containing plumes, which must be contained (typically with smoke-evacuation systems) during the procedure.